1. Field of the Invention
The present invention relates generally to earth anchors and, more particularly, to a lead point for use with a helical earth anchor which is to be installed in frozen or dense soil.
2. Discussion of the Prior Art
It is known to provide a modular screw anchor having a lead point that is non-integral with the main portion of the anchor which carries a load bearing helical blade. Such a construction is illustrated in U.S. Pat. No. 4,334,392, to Dziedzic, and includes a rod made up of a major elongated portion and an earth-penetrating lead, and a modular one-piece anchor member disposed on and operatively coupled to the rod.
In the known construction, the rod is provided with an outwardly extending, circular shoulder which is adapted to engage a hub portion of the anchor member, and the earth-penetrating lead depends from the circular shoulder in a direction away from the hub portion. As disclosed in the noted patent, the lead is in the form of an elongated, generally square section which is obliquely oriented relative to the longitudinal axis of the major portion of the rod and is beveled at its lower end to present a lowermost earth-cutting edge.
Although the known construction performs in a satisfactory manner under many variable conditions, it has been found that when installation of the anchor is attempted in frozen ground or in grounds made up of dense homogeneous earth, the anchor may be prevented from penetrating the earth beyond a certain point due to the resistance presented to the anchor by the frozen or dense earth. Under such circumstances, the known anchor construction has no utility since it may not be properly installed to a desired depth at which it will provide a predetermined tensile load on the rod.
This condition of an anchor losing its utility in frozen or dense earth is especially prominent in anchors of the type which are provided with hollow hubs adapted to be engaged by a wrench member that extends into the hub during installation of the anchor member. In this type of anchor assembly, a relatively large bearing surface area is presented by the anchor due to the increased cross-sectional area of the hub of the anchor member, and this increased bearing surface area causes an increase in the total resistance exerted on the anchor member by the earth during installation.
Further, although the known screw anchor construction includes an earth-penetrating lead having an obliquely oriented design, it has been found that the screw anchor still is capable of being impeded by frozen and dense earth during installation due to the amount of relatively flat bearing surface of the anchor member which exists on the assembly in the vicinity of the circular shoulder of the rod.